Mainframe Developer

iSeries Development Lead

Salary: £58,000 - £62,000

Contract: Permanent, full-time

Location: Hybrid (regular travel to Cardiff required)

We're looking for an experienced iSeries specialist to lead a small development team and keep key exam processing systems running smoothly. It's a hands-on role where you'll guide technical decisions, support a team of five developers and make sure core applications stay reliable for users across the organisation.

What you'll be doing

• Leading the maintenance and modernisation of iSeries systems
• Acting as the lead developer for RPG and COBOL work
• Designing and delivering new features, integrations and system updates
• Overseeing data processing workloads and ensuring outputs are accurate and delivered on time
• Reviewing external software and making sure integrations meet internal standards
• Producing clear technical specs and documentation
• Working with product, BI, research, developers and other internal teams to shape solutions
• Keeping project leads updated on progress and managing priorities within the team
• Supporting users, explaining technical changes in plain language and improving existing processes
• Line managing the iSeries team including workload planning, development and pastoral support

What you'll need

• Strong experience developing in RPG, COBOL, Java or .NET
• Understanding of the AS400 environment (CL, DDS, DB2 etc)
• Ability to design specs, analyse systems and support testing and user journeys
• Experience working with data processing, integrations and legacy modernisation
• Clear communication skills and confidence dealing with a range of stakeholders
• Experience leading or mentoring developers is an advantage

What's on offer

• 25 days annual leave plus 16 additional days
• 28% Pension
• Hybrid working policy
• Supportive working culture with opportunities to develop skills

How to apply

Applications are open to candidates across the UK, though regular time on-site in Cardiff is needed. Closing date is Sunday 11 January 2026 with interviews planned for the following week.